investigate why `java -version` changes to 7 during the jvm8 travis script

[nkuehn]

for some reason 'java -version' returns a JVM8 at the beginning of the travis test script, but towards the end (specifically before the groovy test and before installing groovy) it returns a JVM7 version. I suspect one of the tests in between, e.g. scala.

maybe #20 is the only real solution